Foldable back rest



FIG. 1 is a perspective view of a foldable back rest showing my new design in opened condition; and,

FIG. 2 is a front view of a foldable back rest in a folded condition.

The surfaces or portions of articles not shown in the drawing or described in the specification forms are no part of the claimed design. 

I claim the ornamental design for a foldable back rest, as shown and described. 